Which two characteristics accurately describe x-rays?

X-rays are a form of electromagnetic radiation, which is why they have no mass. Being massless allows them to penetrate various materials, including human tissue, which is crucial in medical imaging. In addition to being massless, X-rays travel at the speed of light, which is approximately 299,792 kilometers per second (or about 186,282 miles per second) in a vacuum. This high speed enables X-rays to cover large distances quickly and contributes to their effectiveness in radiographic imaging.

Other options present concepts that are not aligned with the fundamental properties of X-rays. For example, some options refer to physical characteristics like mass, charge, or visibility, which do not apply. Understanding these properties helps in grasping how X-rays function in medical diagnostics and the principles behind their use in technology.